The present invention relates to an improved mechanical remote control device for operating the channel selector of a television receiver. More particularly, the present invention is directed to such a device that one can be adapted to such selector mechanism, for the purpose of actuating it from a remote position by means of a manually operable pull cord.
It is well understood bother for the viewer of a television receiver to switch the channels of the apparatus, due to the distance which normally separates the viewer from the receiver. The difficulty increases when the viewer is incapacitated for reasons of health and must move from a seat or bed for the purpose of changing channels. This has led to the creation of various remote control methods and devices which allow the changing of channels to be performed from a resting position of the viewer.
Even though such known remote control systems perfectly fulfill their purpose, they are associated with the disadvantage of being very complex and costly. Further, such known systems must be attached to the selector of which they form an integral part. This requires in some cases that the manufacturer of the television receiver include such remote control device within the cabinet, or provide therein sufficient space for a later installation. This is often not possible since each of such devices is substantially different in concept and in structure. Another disadvantage of known devices is that, due to their complex structure, the devices are subject to failure and constant imperfections, which results in high maintenance costs and short useful life.
These difficulties are present in any of the known remote control systems that employ electric, eletromagnetic or sonic energy, since such systems are very costly.
One previously known attempt to provide a mechanical remote control device is shown in U.S. Pat. No. 1,925,991 to Shaw, which describes a device for rotating the control knobs for volume control and for controlling the condenser of a radio receiver, by means of flexible shaft connected to each of such knobs. The operator, situated at a distance from the receiver, rotates the shaft to produce the rotation of the desired knob. The shaft is enclosed within a flexible tube that is not rotatable, and the device is provided with a rotary disk joined to the shaft and operated manually by the user. According to this arrangement, the rotary movement of the disk produced by the operator is transmitted through the flexible shaft or cable to the selector knob. However, such rotation requires a relatively great effort, due to the large friction surface between the flexible shaft and the tubular cover, and further due to the actual twisting to which the shaft is subjected.
U.S. Pat. No. 2,769,233 to Block et al. describes another known mechanical remote control device provided with a pull cord manipulated by a remotely positioned operator for the purpose of actuating a clamp or hammer connected to an indented wheel, in such a manner that each advance of the clamp drives the wheel by a tooth thereof, and consequently the shaft of the selector joined thereto. In this arrangement the device consists of a fixed and stationary element which surrounds the selector shaft and which is firmly joined to the front panel of the set, a second rotary element mounted on the shaft and in front of the first element for producing a cavity between the two, and mechanical means situated within such cavity for transforming linear movement into rotation, through the effect of traction to which the cord is subjected. This arrangement, however, has not proven to be practical, since the device must be placed in position in the factory or by a skilled technician, due to the fact that the apparatus must be disassembled in order to attach the device, and further due to the great inconvenience that the actuating arm of the clamp which is necessarily situated within the cavity must be of a very short length. Therefore, the lever arm is small and produces a very low power. Accordingly, the operator must exert a relatively strong pull on the cord, which may cause movement and even dropping of the receiver. Also, a large portion of the traction or pulling force exerted on the cord is absorbed by the cabinet due to friction and inertia. Consequently, the cord must be thick and strong in order to avoid breaking.